This invention relates to conveyor systems and in particular to induction subsystems for providing controlled separation or gaps between packages being delivered single file to a sortation subsystem for sorting of the packages.
In a warehouse, such as a transshipment distribution warehouse, packages are unloaded from trucks or rail cars bringing product from various sources and reorganized, for example, according to product groupings, for storage of like products in common areas of a warehouse, or according to a particular ultimate destination for reloading onto a trailer or the like. A conveyor system for accommodating this activity conventionally includes many infeed spurs which converge and merge the packages into a single-file of product. The single-filed product is then sorted package by package onto sortation take-away spur lines by a sortation subsystem.
In order to sort packages on the sortation subsystem, it is necessary that the packages be separated by a gap of sufficient length to allow a mechanical sortation mechanism to remove individual packages from the sortation conveyor at the desired point by displacement of the moving package laterally from the sortation line, as the package passes the appropriate take-away line. While a suitable spacing, or gap, is required between packages, any spacing larger than that required to operate the sortation subsystem decreases the capacity of the conveyor system to convey packages.
One technique for establishing gaps between packages is to discharge the stream of packages from an accumulating conveyor onto a series of belts of increasing speed. As the package discharges from one belt to the next, it is accelerated and spaced from the subsequent package. The difficulty with such a system is that the gap is proportional to the length of the package. The result is that, if system parameters are selected to properly gap the smallest packages, wasteful large gaps will occur between longer packages.
Another difficulty that must be addressed in such a system is the merging of packages into a single file for sortation. Because warehouse floor space is usually at a premium, it is disadvantageous to provide an accumulation conveyor between a completely merged line of packages and the sortation subsystem because the required length of the accumulation conveyor would be great. Accordingly, it may be desirable to separate the infeed lines into two or more feed lines each having a short accumulation conveyor and provide the final package merge immediately upstream the sortation subsystem. Multiple accumulation conveyors feeding the sortation subsystem can run at slower speeds than would be required to deliver the same volume of packages from a single accumulation line. This also increases the life expectancy of the conveyor and reduces noise.